Description: Display handle error and quit
Mapped Command:
FUNCTION __HandleError(error,label,procname)
   procname := if(procname == NIL,"Unknown Proc",procname)
   settext()
   clear screen
   do case
   case error == NoSuchLabel
      ? procname + ": No such label: " + label + "!"
   case error == NoLabelsLeft
      ? procname + ": No handles left to create label: " + label + "!"
   case error == NoMemoryLeft
      ? procname + ": No video memory left to create screen save: " + label + "!"
   endcase
   quit
RETURN(Void)